Because, as he said, "Ah intend to squeeze you. Ah don't lahk your kinda people..." He was both greedy and bigoted; and he used the bigotry to justify his greed, as when he said, "...comin' out to his clean country..."

If you saw "Casino," you'll remember somewhat the same argument when the County Commissioner (L.Q. Jones) demands that DeNiro put his useless brother in law back on the casino payroll. DeNiro refuses, and the Commish says, "You people just will never understand that you're here as guests, and that we can ship you back where you came from." That's the same sense of "ownership" (and bigotry, as in "you people") that Geary was expressing to Michael: "We own this state, you don't."